Drug delivery systems are each used to deliver a drug to a specific target region in a person's body to treat a condition in or related to that region in a localized and efficient manner. One example of such a target region includes a portion of the person's circulatory system, including the heart or a portion of the heart.
The heart is the center of a person's circulatory system. It includes an electro-mechanical system performing two major pumping functions. The left portions of the heart draw oxygenated blood from the lungs and pump it to the organs of the body to provide the organs with their metabolic needs for oxygen. The right portions of the heart draw deoxygenated blood from the organs and pump it into the lungs where the blood gets oxygenated. The pumping functions are accomplished by contractions of the myocardium (heart muscles). In a normal heart, the sinoatrial node, the heart's natural pacemaker, generates electrical impulses, known as action potentials, that propagate through an electrical conduction system to various regions of the heart to excite myocardial tissues in these regions. Coordinated delays in the propagations of the action potentials in a normal electrical conduction system cause the various regions of the heart to contract in synchrony such that the pumping functions are performed efficiently.
A blocked or otherwise damaged electrical conduction system causes the myocardium to contract at a rhythm that is too slow, too fast, and/or irregular. Such an abnormal rhythm is generally known as arrhythmia. Arrhythmia reduces the heart's pumping efficiency and hence, diminishes the blood flow to the body. A deteriorated myocardium has decreased contractility, also resulting in diminished blood flow. A heart failure patient usually suffers from both a damaged electrical conduction system and a deteriorated myocardium. The diminished blood flow results in insufficient blood supply to various body organs, preventing these organs to function properly and causing various symptoms.
Various drugs are available to treat such cardiac disorders. Some drugs are most effective when directly applied to the heart, such as to a cardiac region where a disorder originates. Electrical therapies delivered to the heart, such as pacing and defibrillation therapies, have been developed and applied to treat various cardiac disorders including arrhythmia and heart failure. When properly combined, drug and electrical therapies benefit a patient to an extent beyond what is achievable by either drug therapy or electrical therapy alone. Thus, there is a need for a system that efficiently delivers coordinated drug and electrical therapies.